inheritance

Question 1

What are chromosomes

Answer 1

thread like structures of DNA carrying genetic information in the forms of genes located in nucleus. double helix supercoils to form structures called chromosomes

Question 2

How many chromosomes does the human body have

Answer 2

Ordinary human body cells contain 23 pairs of chromosomes. Each chromosome pair is called a homologous pair

Question 3

What is the 23rd pair of chromosomes called

Answer 3

sex chromosomes
In females, the sex chromosomes are the same, a homozygous genotype (XX)
In males, the sex chromosomes are different, a heterozygous genotype (XY)

Question 4

How many chromosomes do Gametes contain

Answer 4

Gametes contain just 23 individual chromosomes

Question 5

What processes rely on DNA

Answer 5

Cell division and protein synthesis both rely on these base-pairing rules because each half of the DNA double helix acts as a template to be copied in order to create a complete new double helix

Question 5

What is DNA

Answer 5

Genetic material found in the nucleus of a cell. The strands are formed from a sugar phosphate backbone with bases joined together by complementary base pairing
Adenine pairs with thymine
Guanine pairs with cytosine

Question 6

What is the structure of RNA

Answer 6

the nucleic acid RNA (ribonucleic acid) is a polynucleotide – it is made up of many nucleotides linked together in a long chain

Question 7

What are the similarities between RNA and DNA structures

Answer 7

RNA nucleotides contain the nitrogenous bases adenine (A), guanine (G) and cytosine (C).
RNA polynucleotide strand is made up of alternating ribose sugars and phosphate groups linked together, with the nitrogenous bases of each nucleotide projecting out sideways from the single-stranded RNA molecule.
RNA molecule is messenger RNA (mRNA), which is the transcript copy of a gene that encodes a specific polypeptide. Two other examples are transfer RNA (tRNA) and ribosomal RNA (rRNA)

Question 8

What are the differences between RNA and DNA structure

Answer 8

RNA nucleotides never contain the nitrogenous base thymine (T) – in place of this they contain the nitrogenous base uracil (U). RNA nucleotides never contain the nitrogenous base thymine (T) – in place of this they contain the nitrogenous base uracil (U)

Question 9

What is a gene

Answer 9

A gene is a sequence of nucleotide bases in a DNA molecule that codes for the production of a specific sequence of amino acids, that in turn make up a specific polypeptide (protein)

Question 10

What are the stages of protein synthesis

Answer 10

Transcription – DNA is transcribed and an mRNA molecule is produced

Translation – mRNA (messenger RNA) is translated and an amino acid sequence (protein) is produced

Question 11

What is Transcription

Answer 11

This stage of protein synthesis occurs in the nucleus of the cell
Part of a DNA molecule unwinds (the hydrogen bonds between the complementary base pairs break)
This exposes the gene to be transcribed (the gene from which a particular polypeptide will be produced)
A complementary copy of the code from the gene is made by building a single-stranded nucleic acid molecule known as mRNA (messenger RNA)
The mRNA molecule leaves the nucleus via a pore in the nuclear envelope

Question 12

What is translation

Answer 12

his stage of protein synthesis occurs in the cytoplasm of the cell
After leaving the nucleus, the mRNA molecule attaches to a ribosome
In the cytoplasm, there are free molecules of tRNA (transfer RNA)
These tRNA molecules have a triplet of unpaired bases at one end (known as the anticodon) and a region where a specific amino acid can attach at the other
There are at least 20 different tRNA molecules, each with a specific anticodon and specific amino acid binding site
The tRNA molecules bind with their specific amino acids (also in the cytoplasm) and bring them to the mRNA molecule on the ribosome
The triplet of bases (anticodon) on each tRNA molecule pairs with a complementary triplet (codon) on the mRNA molecule
Two tRNA molecules fit onto the ribosome at any one time, bringing the amino acid they are each carrying side by side
A peptide bond is then formed between the two amino acids
This process continues until a ‘stop’ codon on the mRNA molecule is reached – this acts as a signal for translation to stop and at this point the amino acid chain coded for by the mRNA molecule is complete
This amino acid chain then forms the final polypeptide (protein)

Question 13

What is a gene

Answer 13

A gene is a short length of DNA found on a chromosome that codes for a particular characteristic

Question 14

What are Alleles

Answer 14

Alleles are variations of the same gene
As we have two copies of each chromosome, we have two copies of each gene and therefore two alleles for each gene
One of the alleles is inherited from the mother and the other from the father

Question 15

What is a genotype

Answer 15

The combination of alleles that control each characteristic is called the genotype.

Question 16

what is a phenotype

Answer 16

The observable characteristics of an organism (seen just by looking - like eye colour, or found – like blood type) is called the phenotype

Question 17

What the difference between a dominant and recessive Alleles

Answer 17

A dominant allele only needs to be inherited from one parent in order for the characteristic to show up in the phenotype
A recessive allele needs to be inherited from both parents in order for the characteristic to show up in the phenotype.

Question 18

What is a Homozygous

Answer 18

If the two alleles of a gene are the same the individual is homozygous (the same)

Question 19

What is Heterozygous

Answer 19

If the two alleles of a gene are different the individual gene is described as being heterozygous